The present invention relates to an apparatus and a method for processing container closures.
As generally known, in the food industry and in particular in the field of aseptic filling of containers with beverages and in the field of aseptic food packaging, there exists a need to sterilise the containers both internally and externally before they are filled.
Sterilisation is generally achieved using chemical agents, e.g. hydrogen peroxide, which can be used on surfaces of every type, such as paper, plastic, metal or organic materials.
To ensure that filling takes place in aseptic conditions it is necessary to sterilise not only the containers but also their closures, for example caps or stoppers, which serve to seal the containers at the end of the filling process.
In particular, the present invention is concerned with closures which are screwed to respective containers to be connected thereto.
Therefore, known apparatuses comprise a sterilization unit, for sterilizing the closures, and a capping unit, having screwing means active on the closures for connecting them on correspondent containers, applying a predetermined torque. Further, the sterilization unit comprises means for spraying on the closures a hot sterilization fluid. Depending on the sterilizing process that is implemented, the fluid can be heated so that it becomes vaporized. Therefore, the closures are heated during the sterilization step.
In addition, said apparatuses comprise a guide member, interposed between the sterilization unit and the capping unit.
The guide member is configured is such a way that a plurality of closures can be arranged in the guide member at the same time. This is important because the processing of the closures from the sterilization unit to the capping unit is run continuously, but the sterilization unit and the capping unit may have different processing rates. Hence, the guide member also acts as a buffer.
However, these known apparatuses have the following drawbacks.
Although the force applied to the closures in the capping unit, to screw them to the containers (closure torque), is the same for all the closures, the force required to open the containers, i.e. to remove the closures from the containers (opening torque) may vary greatly from case to case.
In fact, the opening torque of a given closure depends on the closure torque applied to that closure and on the temperature of the closure at the time the closure torque was applied (i.e. the temperature of the closures in the capping unit).
Hence, the temperature of the closures in the capping unit varies, depending on the time that undergoes since they exit from the sterilizing unit, i.e. the time the closures stay in the guide member.
In fact, as soon as the closures exit the sterilizing step, they begin to cool down, because they are not anymore subjected to the hot fluids present in the sterilization unit (i.e. the sterilization fluid and, in the case of dry sterilization technology, hot air having the purpose of drying the closures).
The dispersion of distribution of the temperature of the closures in the capping unit (from which the dispersion of distribution of the opening torque results) is particularly evident in case the apparatus is stopped as a consequence of a failure (or of any other reason).
In fact, in the case of a stop of the apparatus, the closures present in the sterilization unit are discharged (because they would be damaged if subjected to the hot sterilization fluids for too long) and the closures arranged in the guide member remain there until the cause of the stop is removed.
Therefore, one of the main drawbacks of the known apparatuses is that the opening torque is not uniform, with the consequence that some closures are too loose, and some others are too tight.